1. Field of Invention
This invention has to do with splash guards or fenders as applied to bicycles in particular.
2. Description of Prior Art
It is currently popular, both for practical and aesthetic reasons, for bicycles not to have any type of wheel fenders. As mentioned in the prior art, this presents no difficulty under dry street conditions. If the bike is ridden on wet streets, however, both wheels will pick up water and mud an throw them on the rider. If the rider is wearing a rain suit the problem is less severe, but this suit may be hot and inconvenient and will not protect the face and hair. The streets may be wet long after the rain stops.
Conventional fenders generally cover a large portion of the wheel circumference and are installed more or less permanently due to the difficulty of installation. They also generally cover the wrong part of the wheel unless they cover almost all of it. Most fenders seem to be designed on the incorrect assumption that the spray leaves the wheel radially. White's extendable fender design in U.S. Pat. No. 4,319,763 would have to be greatly lengthened on both the front and back wheel in order to be effective. This is so since the spray leaves the wheel tangentially. This means the spray that hits the rider comes from the upper back end of the rear wheel and the lower back end of the front wheel. The extendable design just mentioned would become unwieldy, both structurally and from the point of view of beauty if it were lengthened.
All of the fenders may be analyzed for performance by drawing spray lines tangentially from the wheels to see which spray is blocked. All of the spray lines actually follow a parabolic trajectory with respect to the moving bicycle (neglecting wind resistance). But straight lines may be used as an approximation at most positions. The rear of the wheel is one exception. Spray from here is thrown up in the air which only hits the rider on the downward path.
Three other prior art fenders to be discussed so seem to grasp that the spray leaves the wheel tangentially, but still would not do the job of blocking the spray adequately. Two are from patent literature and one is on the market unpatented apparently.
The marketed fender just mentioned is available in at least two similar forms. By one company they are known as "Deflector Shields" and by another as "Splash Mate and Rack Mate". They consist of removable, flat plastic plates.
The rear ones only work on bikes with rear racks, which very few bikes have. They cover the top of the rack and block some of the rear wheel spray. However, since bike racks don't extend to the rear of the wheel, much of the wheel at an important area is left uncovered. Therefore, the rider will pick up a large amount of the rear wheel spray even with the plate in place.
The front plates attach to the down tube by the front wheel. They do not come close to blocking all the spray. On both brands the feet and lower legs are not protected nor is the face if it is near the handlebars. And the protection it does provide is only good while the wheel is more or less in a straight ahead position since the plates are attached to the frame and do not move with the wheel during turns. In order to do any good at all these plates have to be very large and since they are oriented almost square into the wind they may result in a significant wind resistance.
One of the mentioned patented (U.S. Pat. No. 4,243,241) but unmarketed fenders by Davis is just for the rear wheel. It consists of a flat plastic piece molded onto the hook-shaped end of a support arm. The plate is oriented radially in a plane perpendicular to the wheels. It is far too small to adequately protect the rider, but if it were large enough to do the job it could not be moved under the seat by pivoting as designed. It is oriented wrong to block the most spray with the least amount of fender. It also has material dragging on the tire in an attempt to remove mud and water. This is of questionable value and would increase bike riding resistance, particularly with mud. The clamped connection to a seat stay may not give enough resistance to rotation about the seat stay axis since many similar connections on bikes now slip readily.
One of the main ideas of Davis' splash guard is that it can be pivoted up under the seat during dry weather to make it unobtrusive. Some would question whether that action renders it much less noticeable.
The last of the patented but unworkable fenders mentioned is by Gruter (European patent announcement #83101278.6). This fender for front and rear consists of a short circular arc fender piece curved to follow the wheel and cupped in cross-section, which really looks like a piece cut off of a conventional bike fender. This is supported by a pair of hinged support arms with elastic clamp ends that attach to the seat stays or the front fork members.
Neither the front nor the rear fender are likely to work as shown. They are much too small to work properly in the configuration shown. It is even easy to see from the patent sketch itself that neither fender comes close to blocking all the spray that would hit the rider.
The rear one would have to be about twice as long in its present configuration to catch the spray from the rear of the wheel that would fly up in the air and then arc down onto the rider's back or even to block more direct spray that would hit the rider if he were shown sitting up in the sketch instead of hunched over.
The front fender is in even a worse situation as far as size. Its length would have to be nearly three times that shown in the patent sketch in the configuration shown in order to protect the rider. In the first place the bike pedal is shown higher and closer to the wheel than its worst case situation which is at the bottom of the stroke. So the fender would have to extend down almost under the wheel to protect the foot. This would be bad if the bike went over an obstruction such as a curb or through a pothole. The fender would be torn off. Since, as shown, it doesn't give spray protection from half way up the lower leg up to the face, it would have to be extended almost up to the closest point between wheel and frame downtube. This may be readily seen by drawing tangent lines from the wheel circumference to the rider as was done on the lower part of the wheel.
Both front and rear fenders would become too heavy and unwieldly, not to mention unsightly if they were increased to the true size needed to do the job in this configuration. It would be difficult to hold such a large, close-fitting fender in perfect alignment to keep from rubbing against the tire with only two support arms, especially with the snap-on frame connection. Furthermore, it is doubtful that the snap-on frame connection shown would support even the weight of the small fenders shown, with impact loading from bumps.
Even assuming that it did work it could not be installed and removed in seconds as claimed in the patent document. The patent sketch shows at least four screws which must be tightened to install each fender which also would seem to be require that tools be carried. Finally, this could not likely be used on off-road bicycles as it is too close to the ground in front to avoid obstructions and follows the wheel closely, as a conventional fender does, and so would clog with mud in muddy conditions.
One of the stated objectives of Gruter's fender is that the support arms may be folded up into the fender pieces, which may then be carried in the rider's pockets until needed. However, if the rider is going to have to carry them, it would seem much more convenient to carry them deployed on the bike rather than folded in the pockets. If it didn't look like rain they would likely be left at home instead of carried on the rider.
The history of bicycle fender design includes an array of fenders which look good but do not work. And no matter how good a fender looks it is of no use to a bicyclist if it doesn't work as claimed.